PMM-14231 - Add backup type to captured PBM metrics

[theTibi]

https://jira.percona.com/browse/PMM-14231

• Links to relevant pull requests

[JNKPercona]

Server docker: perconalab/pmm-server-fb:PR-4056-b34fac8
Client docker: perconalab/pmm-client-fb:PR-4056-b34fac8
Watchtower docker: perconalab/pmm-watchtower-fb:PR-4056-b34fac8
Client tarball: https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4056-b34fac8.tar.gz
Staging instance: https://pmm.cd.percona.com/job/pmm3-aws-staging-start/parambuild/?DOCKER_VERSION=perconalab/pmm-server-fb:PR-4056-b34fac8&CLIENT_VERSION=https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4056-b34fac8.tar.gz

[JNKPercona]

Server docker: perconalab/pmm-server-fb:PR-4056-b34fac8
Client docker: perconalab/pmm-client-fb:PR-4056-b34fac8
Watchtower docker: perconalab/pmm-watchtower-fb:PR-4056-b34fac8
Client tarball: https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4056-b34fac8.tar.gz
Staging instance: https://pmm.cd.percona.com/job/pmm3-aws-staging-start/parambuild/?DOCKER_VERSION=perconalab/pmm-server-fb:PR-4056-b34fac8&CLIENT_VERSION=https://s3.us-east-2.amazonaws.com/pmm-build-cache/PR-BUILDS/pmm-client/pmm-client-PR-4056-b34fac8.tar.gz

[JNKPercona]

API tests have failed: https://pmm.cd.percona.com/job/pmm3-api-tests/3836/

[JNKPercona]

API tests have failed: https://pmm.cd.percona.com/job/pmm3-api-tests/3837/